Salient Pole Machine Cooling via Segmented Fans
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Solution Overview
Problem
Salient pole machines, such as generators and motors, face inefficiencies due to windage losses from large air flow requirements and unfavorable geometry, leading to high operating costs and greenhouse gas emissions, necessitating improved design for reduced losses and increased efficiency.
Innovation Solution
The implementation of small induction motor-driven fans for cooling and the use of composite inter-pole and end coil caps to minimize turbulent losses, along with independent fan assemblies, reduces windage losses and enhances efficiency by reducing drag and heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If large air flow is used for cooling, then cooling effectiveness is improved, but windage losses increase
Solution Approach 1:
The cooling system is segmented into multiple independent fan assemblies (typically 3-4 fans) distributed around the stator perimeter, each handling a portion of the cooling task. This segmentation allows for more efficient local cooling patterns and reduces the total air flow resistance compared to a single large fan system, thereby reducing windage losses while maintaining cooling effectiveness.
Solution Approach 2:
Cooling ducts and air passages are introduced as intermediary structures to guide air flow efficiently from the fan assemblies to the specific cooling locations (pole faces, coil end regions). These intermediaries optimize the air flow paths, reducing turbulence and pressure drops, thus lowering windage losses while ensuring effective heat removal.
2Ease of manufacture
If unfavorable geometry is used in salient pole design, then manufacturing is simplified, but windage losses increase due to high pressure drops
Solution Approach 1:
The air flow parameters (velocity, pressure, flow direction) are optimized through carefully designed duct geometries and fan positioning. By changing these parameters, the system achieves efficient cooling with reduced pressure drops, overcoming the unfavorable geometry of salient poles while maintaining manufacturing feasibility.
Solution Approach 2:
Curved or rounded air passages and duct transitions are used instead of sharp angles to reduce flow separation and turbulence. This curvature principle minimizes pressure drops in the cooling air flow paths, reducing windage losses while the overall pole geometry remains suitable for manufacturing.
3Temperature
If shaft mounted cooling fans are used, then cooling is provided, but turbulent losses and drag increase
Solution Approach 1:
The cooling fan function is extracted from the rotating shaft assembly and relocated to stationary fan assemblies mounted on the stator. This extraction eliminates the turbulent losses and drag associated with shaft-mounted fans, as the stationary fans create more controlled, laminar air flow patterns while still achieving effective cooling of the rotor and stator components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in lower operating costs, reduced heat production, and extended machine life due to lower temperatures, while providing significant fuel savings and improved reliability.
Implementation Method 1
small induction motor driven fans were used to cool the unit
Implementation Method 2
composite inter-pole caps and composite end coil caps were used to lessen drag
Data Source
AI summary
A salient pole machine and method of forming the same comprising a rotating field assembly and at least one inter-pole cap connected to the rotating field assembly and/or at least end coil cap connected to the rotating field assembly. Each inter-pole cap preferably includes a top surface that has a curvature and/or at least one cavity. Each end coil cap may include at least one support. The salient pole machine may also include at least one fan assembly independent of the rotating field assembly. In a preferred embodiment, the salient pole machine includes at least one mounting plate, wherein each fan assembly is mounted on the mounting plate. The inter-pole caps and the end coil caps preferably comprise composites, polymers, alloys, ceramics, or naturally occurring materials.